Oscillation generator



Nov. E6, 1937. K, FRITZ l 2,099,300

osCILLATIoN GENERATOR Filed May 7, 1956 INVENTOR r4 ZvBY KARLTFRUZ /Luzrg ATTORNEY Patented Nov. 16, 1937 UNITED STATES PATENT OFFICE OSCILLATION GENERATOR Germany Application May 7, 1936, Serial No. 78,306 In Germany May 9, 1935 11 Claims.

The present invention relates to an oscillation generator for producing simultaneously Va plurality of waves of different frequencies.

Transmitter arrangements are known in which a two tube circuit is used for the alternative pro duction of two different frequencies lying near each other. To avoid mutual interference between the transmitters, the electron tubes producing the different frequencies are fed in opposite phase from a source of alternating potential, so that only the tube whose anode receives the positive alternation is at the moment capable of producing oscillations. The high frequency oscillations are thereby modulated at the frequency of the alternating plate potential` Short wave transmitter arrangements are also known in which a two tube circuit is used for the simultaneous production of two different waves. The grids and plates of such tubes are connected across Va parallel wire system, and in parallel to this parallel wire system there is placed unsymmetrically with respect to the two tubes, a variable capacitance, so that the original push-pull connection is transformed into two separately operating transmitters of different frequencies.

All these known arrangements require two tubes,.each for producing a different frequency. If,due to any causes, variations in the operating voltages or capabilities of emission, or aging phenomena of a varying kind occur (and it must be expected that these phenomena will appear in these tubes in varying degrees) then the intensity or the frequency of the produced oscillations will be varied, to an appreciable extent.

In my oscillation generator as herein shown only a single tube need be used, although, if desired, several tubes in parallel may be used. With a suitable choice in the operating conditions oscillations of different frequencies may be generated either simultaneously or sequentially at a given keying rate.

. Furthermore, the operating conditions can be so chosen that the tube oscillates simultaneously at different-frequencies the ratio between which is g approximatelyr equal to a whole number.

Moreover, it is also possible to produce in rapid alternation two or a greater number of different waves in succession, differing from each other by a relatively small frequency `value only.

In the following paragraphs, the invention will be elucidated primarily in connection with magnetron tubes, since with these generators the possibilities in producing multi-wave oscillations, can be best explained. However, other types of electron discharge tubes may be used if desired.

My invention will now be explained in detail, reference being made to the accompanying drawing, in which Figure 1 shows diagrammatically the magnetron circuit suitable for generating waves of a plurality of frequencies;

Figs. 2, 3 and 4show modified magnetron circuits, each suitable for achieving the objects of the invention;

Fig. 5 shows still another embodiment of the invention; and

Fig. 6 is a diagram which is referred to in explaining the theory of operation of my invention.

In Fig. 1 there is shown, by way of example, a magnetron circuit which produces simultaneously waves of a plurality of frequencies. The frequencies are preferably harmonicall'y related, or nearly so. A magnetron tube with four anodes A1, A2, A3, and A4 arranged symmetrically with respect to the cathode K is combined with a Lecher-wire system to form a transmitter. The opposite anode parts A1 and A3 are joined across a bent connection V1, and the other anode parts A2 and A4 are connected by the conductor V2. The parallel wire system has its connection line Lz placed at the center of the connection strap V2. The operating conditions can, in the hitherto known manner, be so chosen that the entire system oscillates in its fundamental wave. Then a single voltage node exists at the tuning bridge B across which the plate potential will be applied from'the direct current source l. Oscillations are generated Whose frequency is dependent upon the inter-electrode travel time of the electrons in the magnetron. 'I'hrough a proper choice of the operating conditions I have found that an upper harmonic may simultaneously be generated.

The power of the individual waves can be adapted to the respective requirements by a corresponding choice of the operating conditions. The produced oscillations can be separated at will or they may be combined in any desired manner. For instance, resonance circuits, filters, or tuned radiators may be employed in the output circuit.

Fig. 2 shows a magnetron tube having four anodes especially suited for putting the idea of the invention into practice. In this case, the parallel wire system L1 L2 is connected to the anodes in an unsymmetrical manner so that two systems having different natural frequencies f1 and f2, are thereby obtained. There is obtained on the one hand, a circuit having a high natural frequency f1 and shown in Fig. 3. The anodes A1 and A4 oscillate in opposite phase, by virtue of the inductance of the circuit which is composed of the connection bend V1, connection line L1, line L2, and connection bend V2. On the other hand, oscillations of a lower natural frequency f2 are obtained as shown in Fig. 4. The inductance of the oscillatory circuit presented'by the anodes A2 and A3, which oscillate in opposite phase, consists only of the parallel wire system L1, L2.

This idea may be further developed by con-l necting a magnetron Whose anode is divided into six parts, with the inductance of the oscillatory circuit in such an unsymmetrical fashion that three individual circuits having different natural frequencies are obtained. For a great number of special purposes such as, for instance, for the production of directive rays, it is desirable to obtain from a single generator tube, alternatively several different waves lying very closely to each other, for instance )(1:50 cm., )\2=5O.5 cm. etc. adjacent waves can still be properly separated from each other in an appropriate circuit, and following this separation may for instance be differently modulated. The antennae suitable for such closely situated wave lengths differ from each other very slightly as regards dimensioning, so that it will in practice be possible to recombine the waves after they have been separately modulated and thus to send out these waves from a single radiator.

In order to carry out this part of the invention, the operating conditions can be so chosen in regard to viewpoints to be described later, that in case of a magnetron with multi-partite anode, several waves deviating from each other by only a small value in the frequency and produced apparently at the same time, will be found in a wave meter that is loosely coupled to said magnetron. A closer study shows, however, that in most cases the Waves are not set up exactly at the same time, but alternate in a rapid rhythm for instance in the rhythm of the high-frequency such that the indicator of the wave meter can no longer respond thus making it appear asif the Waves were produced simultaneously. 4

As long as this alternation remains above the audible frequency it will not, under ordinary circumstances, have any adverse effect. Itis seen that the integral of the energies of the individual frequencies successively appearing in the receiver can practically be considered, equal to the sum of the energies of the individual waves, assuming that the latter have a smaller amplitude, but act simultaneously.

As a further feature of the invention, I provide means for controlling at will the alternate production of the different frequencies.

There exist several causes for the appearance of multiple Waves, these causes being to some extent independentof each other. As a condition to be generally observed it is to be borne in mind that the setting up of the one oscillation (M) must so change the operating conditions of the generator that the condition of excitation for another oscillation (A2) becomes more favorable and vice versa, in order that the performance may control itself.

A plausible explanation of the theory of multiple wave production maybe:

(l) That a magnetron operates on two closely Y coupled circuits which are slightly detuned, as shown in Figs. 2, 3 and 4.

(2) That, although only a defined system is present, the position of the phase of the electron course relative tothe oscillatory performance, influences the wave length by'a small'value. Thus Such by means of the magnetic field which determines the travel time of the electrons, it is possible to expand the wave lengths.

(3) That an electrostatic influence exists between the anode segments such as to cause the electrons to travel in separate groups or clouds. Hence the electron density and hence the wave length can be controlled, if desired, by using a Y magnetic eld whose axis is transverse to the axis of the tube electrodes.

. For the purpose of producing directive rays and also for other purposes it is important to provide modulating means for producing a variation in the generated wave length in sudden steps. Either amplitude, frequency or phase modulation may be so employed and may be applied to the oscillator either by varying the plate potential, or by varying the magnetic eld in density or direction.

In carrying out my invention I have further found it to be desirable to Vary the frequency of oscillations by sudden steps. Two working points for the generation of oscillations are, therefore, obtained and a sudden shift is made from one working point to the other. to fix the operating characteristics so that aA break will occur between the working points. Barkhausen ha-s shown in his book Elektronenroehren, vol. 2, page 104, published in 1928, thatv two working points are obtainable with an interruption in the tube characteristic lying between these working points.

Thus even when the means for controlling the frequency of oscillations is varied gradually between two limits, the oscillations themselves suddenly cease and start again as the tube operation is caused to vary from one to the other of the characteristic working points.

In the magnetron a break in the operating characteristic is obtained by a suitable choice of the plate potential and of theV magnetic field strength when the angle yorV between the magnetic eldraxis and the symmetrical axis of the electrode system becomes equal to zero. See Fig. 6. Between the plus and minus values of a there lies a more or less pronounced region of discontinuity in the characteristic.Vv The Wave lengths on the one, and on the other side of the break are not identical, since the operating conditions differi With additional circuit meansvit is possible toV obtain for the individual waves the desired frei quency value and the desiredam'plitude.

Fig. 5 represents a circuit by way of example. The Working conditions of a magnetron having an anode divided into two parts may be so varied by means of a magnetic cross field modulated at a superaudible rate, that two waves are succes# sively produced having Vdifferent frequencies. 'I'hrough special tuning circuits I and I I the alternately generated wave lengths A1 Vand Az are filtered out. They may then be modulated separately, and thereafter again applied to va common radiator. y Y W The idea of Athe present invention is not limited to the examples herein shown and'described.

I claim: l

l. An oscillation generator having anelectron discharge tube of the magnetron type, a linear cathode and a plurality of anodes in said tube, a magnetic field producing' means adjacent said tube, conductors interconnecting certain of said anodesV in pairs, a Lecher-wire system connected to said conductors, and tuning means such that a plurality of resonant conditions is providedby It is also necessaryl said lecher-wire system in combination with portions of said conductors, thereby to determine one frequency of oscillations to be delivered by two certain anodes, one in each pair thereof, and to determine a different frequency of oscillations to be delivered by two other anodes, one in each pair thereof.

2. An oscillation generator according to claim 1, and having means for varying the working conditions of said tube between two points on the curve characteristic of said tube between which the curve is interrupted.

3. An oscillation generator according to claim 1, and having means for rapidly shifting the frequency of the oscillations generated between two separated frequency values.

4. An oscillation generator according to claim l, and further characterized by disposing the connections between said Lecher-wire system and the conductors which interconnect certain anodes in such manner that a longer circuit is provided between two certain anodes of respectively different pairs than the circuit interconnecting two remaining anodes of respectively different pairs.

5. An oscillation generator according to claim 1, and having means for producing oscillations of two different frequencies simultaneously.

6. An oscillation generator according to claim 1, and having means for producing oscillations of two frequencies harmonically related to one another.

7. An oscillation generator comprising a magnetron discharge tube having a cathode and a plurality of segmented anodes, a Lecher-wire system having two parallel conductors, one of said conductors being connected to certain of said anodes in parallel and the other of said conductors being connected to the remainder of said anodes in parallel, anodes which are connected to one of said conductors being diametrically opposed to one another, while anodes which are connected to the other of said conductors are also diametrically opposed to one another, and means for exciting the electrodes of said tube with suitable potentials for causing the tube to simultaneously generate waves of different frequencies.

8. An oscillation generator according to claim '7 and having said Lecher-wire system tuned in reference to the resonant characteristics of the tube electrodes and of the connections thereto whereby the waves simultaneously generated are harmonically related to one another.

9. An oscillation generator comprising a magnetron discharge tube having a cathode and a plurality of segmented anodes, a Lecher-wire system having two parallel conductors, one of said conductors being connected to certain of said anodes in parallel and the other of said conductors being connected to the remainder of said anodes in parallel, anodes which are connected to one of said conductors being diametrically opposed to one another, while anodes which are connected to the other of said conductors are also diametrically opposed to one another, and means for exciting the electrodes of said tube with suitable potentials for causing said tube to alternately generate waves of different frequencies.

10. An oscillation generator according to claim 9 and further characterized in that said Lecher-wire system, and the interconnections between the same and said anodes, are so tuned as to enable said generator to develop frequencies differing from each other by a relatively small frequency Value.

11. An oscillation generator in accordance with claim 9 and further characterized in that means are provided for causing said generator to deliver oscillations the frequency of which is rapidly shifted from one value to another during a gradual variation of the working point along the tube characteristic.

KARL FRITZ. 

